PROCEEDINGS OF SOCIETIES. 257 



its constitution and structure, and the many opinions that may originate 

 from the observations ujjon it ; whether the hilum, or central point 

 seen on its surface is due to the adhesion of the starch-granule to the 

 cell- wall which contains it ; whether it is a cavity, or a nucleus, or 

 simj)ly resulting from a i^henomenon of the refraction of light ; 

 whether the concentric markings are due to layers suj)erimposed 

 on the first-formed material, or deposited within each other as newly 

 formed, or are merely due to the plaitings or foldings-in of a vesicular 

 membrane ; whether the granule is contained in an envelope of denser 

 material, or whether it is of a homogeneous structure throughout. It 

 illustrates also the effects of various modes of illumination as seen by 

 transmitted, reflected, or polarized light. 



The origin of life is now a very prominent study, and embraces 

 very many hyjiotheses which depend very much on microscopic obser- 

 vation for their tenure ; the question of the mode of origin of living 

 matter being inextricably mixed up with another i^roblem as to the 

 cause of fermentation and putrefaction. Baron Liebig holds that fer- 

 mentation is purely a chemical process, but the doctrine of M. Pasteur 

 maintains that fermentation can only be initiated by the agency of 

 living things — omne vivum ex vivo — the theory of sj)ontaneous genera- 

 tion. Again, there is the theory of heterogenesis, which imagines 

 that when the vital activity of any organism is on the wane, its consti- 

 tuent particles, being still portions of living matter, are capable of 

 individualizing themselves, and growing into the low organisms in 

 question ; and, again, a new theory by Professor Bastian, that new life 

 may burst forth, de novo, in certain fluids containing organic matter. 

 These hypotheses, however, really range themselves under the vital 

 and the material doctrines, and it is for the microscope to solve the 

 question. 



Of all subjects of immediate and vital interest to the community at 

 large, in which the microscope must necessarily again be the j^rincipal 

 and chief arbitrator, there is none so important as the consideration of 

 contagious diseases. With the Asiatic cholera at our gates, it is indeed 

 well that we should know what we have to contend with, for the know- 

 ledge of a disease is its cure. At present the germ theory of disease 

 is the prevailing one, and disinfectant treatment, and disinfecting pre- 

 cautions, are the chief reliances of the day ; but we fail to find from 

 late experiences that the totality of zymotic diseases is diminishing, 

 and there are many who have yet held back from the accej)tance of 

 this theory, denying the proofs as not yet demonstrated ; and here we 

 have again the never-failing aid of the microscope in its analytical 

 power to judge of what we can apply to its investigation. If we can 

 only prove the existence of these germs as a modus propagandi, we 

 have not only a ready means of explaining the spread of these diseases, 

 but should also be armed with the means of destroying them, and the 

 prevention of the scourging epidemics with whicli the world has ever 

 been afflicted. The vital importance of these inquiries may be realized 

 by the known results, for we learn from statistics that the deaths from 

 zymotic diseases in England and Wales amount to upwards of 111,000 

 per annum, out of a population of 22,000,000, the total deaths being 



